Battery Charging - how to test

[RickyRobert]

Have a relatively new Montana 5th wheel with the Solar Flex System. Apparently I have destroyed two very expensive AGM batteries by over-draining them. Would appreciate any help on how I can diagnose the charging system - firstly, when connected to a 50 amp shore power supply (such as I am now in inside winter storage), secondly, if out in the sun when the Solar is working, and thirdly, if I am running the factory installed generator. What "line" to the batteries should I be testing on, and am I looking for voltage or amperage? And I am assuming that the 12V supply switch in the tank valve area must be set to "on". Thanks from a newbie to this facet of RVing.

[Speck56]

I have the factory installed solar on my 3761FL, but it has never shown whats coming from the panels. I am looking for the MPPT controller also, hope there is a loose connection their

[AZ Traveler]

Your level up panel can provide battery voltage. Check it when hooked to shore power or the genny. It should be above 13 v if your converter is working. If not, check the converter cb.

Are you sure you didn't run the batteries down when not hooked to shore power? You want to disconnect the batteries if the are being stored.

[RickyRobert]

Thanks for the tip regarding the levelling systems display panel. I would have thought that since my inside climate controlled storage includes 50 amp plug in (line 1 is 124 volts and line 2 is 121), that this would engage the battery charging system making it unnecessary to disconnect the battery. Question follow-up - Should the Solar system not charge the battery as well? I guess that I can read off the battery voltage from its display panel as well? Would still like to know which line feeds the charge to the battery to check what its charging amperage is coming through at. Thanks again.

[AZ Traveler]

Originally Posted by RickyRobert

Thanks for the tip regarding the levelling systems display panel. I would have thought that since my inside climate controlled storage includes 50 amp plug in (line 1 is 124 volts and line 2 is 121), that this would engage the battery charging system making it unnecessary to disconnect the battery. Question follow-up - Should the Solar system not charge the battery as well? I guess that I can read off the battery voltage from its display panel as well? Would still like to know which line feeds the charge to the battery to check what its charging amperage is coming through at. Thanks again.

Your solar should charge if the rig is outdoors in the sunlight.

[66 Galaxie]

Originally Posted by RickyRobert

Thanks for the tip regarding the levelling systems display panel. I would have thought that since my inside climate controlled storage includes 50 amp plug in (line 1 is 124 volts and line 2 is 121), that this would engage the battery charging system making it unnecessary to disconnect the battery. Question follow-up - Should the Solar system not charge the battery as well? I guess that I can read off the battery voltage from its display panel as well? Would still like to know which line feeds the charge to the battery to check what its charging amperage is coming through at. Thanks again.

If it's sunny and the batteries need charge, the solar should be charging. It's not wired through the disconnect so, if the fuse is good and the chargers are on, it should be working.

There's six pieces of information on the remote:

Top Left: Panel Voltage (should be 25-35v if working)

Top Middle: Amperage supplied by panels (any where from 8.5 to 0 ffrom a single panel)

Top Right: Watts (power provided)

Bottom Left: Output Voltage from Charger (should be slightly higher than actual battery voltage)

Bottom Middle: Amperage to the battery (0-30 may be zero if batteries are full)

Bottom Right: Charger state (OFF, BLK, ABS, FLT, STBY)

[DadsHemi]

If your connected to shore power your solar system won’t charge your batteries, shore power and your gen provide power to your breaker panel which as your converter that charges your batteries. You should be able to take the terminals off Your batteries and check amperage on the leads. As far as your solar power I would think the controller allows charging when not connected to shore power or your gen.

[kowbra]

Originally Posted by RickyRobert

Have a relatively new Montana 5th wheel with the Solar Flex System. Apparently I have destroyed two very expensive AGM batteries by over-draining them. Would appreciate any help on how I can diagnose the charging system - firstly, when connected to a 50 amp shore power supply (such as I am now in inside winter storage), secondly, if out in the sun when the Solar is working, and thirdly, if I am running the factory installed generator. What "line" to the batteries should I be testing on, and am I looking for voltage or amperage? And I am assuming that the 12V supply switch in the tank valve area must be set to "on". Thanks from a newbie to this facet of RVing.

I think the best system is to install a proper battery monitoring system and the appropriate shunt to go with it. This will give you all the information you need and then some. You can also pair it to an app on your phone for remote monitoring.

For example, you want to know not just what is going in (which charging source, charging rate, and totals over time) but also the discharging rate and amounts. A big contributor to ruined batteries due to discharging them too much is not being aware of all of the small things that may drain a little at a time. And, if you are boondocking, knowing your power usage will help to optimize when to charge with the generator and when to let the solar system charge. I imagine that could really save some propane usage once you start using it.
Maybe a comparison is having a fuel gauge and using the "instant mpg" gauge on your vehicle... that is a lot more accurate and up to date than a stick in the tank, and can help you drive in a way that saves energy also.

For the Montana Super Solar Flex system, they include the highly rated Victron BM-712.
https://www.victronenergy.com/batter.../bmv-712-smart
and, an option to purchase here...
https://www.amazon.com/Victron-Energ.../dp/B075RTSTKS

We used a competing product in a prior 5th wheel, and I would not be without a battery monitor now. Our new Montana has the Victron as above, and it really does help to monitor and know how to properly charge and protect your batteries.

Hope that helps!
Brad

[Billyj571]

Originally Posted by kowbra

I think the best system is to install a proper battery monitoring system and the appropriate shunt to go with it. This will give you all the information you need and then some. You can also pair it to an app on your phone for remote monitoring.

For example, you want to know not just what is going in (which charging source, charging rate, and totals over time) but also the discharging rate and amounts. A big contributor to ruined batteries due to discharging them too much is not being aware of all of the small things that may drain a little at a time. And, if you are boondocking, knowing your power usage will help to optimize when to charge with the generator and when to let the solar system charge. I imagine that could really save some propane usage once you start using it.
Maybe a comparison is having a fuel gauge and using the "instant mpg" gauge on your vehicle... that is a lot more accurate and up to date than a stick in the tank, and can help you drive in a way that saves energy also.

For the Montana Super Solar Flex system, they include the highly rated Victron BM-712.
https://www.victronenergy.com/batter.../bmv-712-smart
and, an option to purchase here...
https://www.amazon.com/Victron-Energ.../dp/B075RTSTKS

We used a competing product in a prior 5th wheel, and I would not be without a battery monitor now. Our new Montana has the Victron as above, and it really does help to monitor and know how to properly charge and protect your batteries.

Hope that helps!
Brad

Do I need to buy 2 BM-712 ??? I have 4 6V Trogan T-105’s do you recommend a temperature sensor

[kowbra]

Originally Posted by Billyj571

Do I need to buy 2 BM-712 ??? I have 4 6V Trogan T-105’s do you recommend a temperature sensor

No, the battery monitor installs inline. It also needs a shunt to work properly.
Search "victron bmv-712 installation instructions"

I've never had a temperature sensor; I know others who do monitor that though, so may be a good thing.
You have good batteries, and you likely know this, make sure you check the water levels monthly. Especially when they are charging in hotter weather they can need topping up with quite a bit of water.

Brad

[Ren]

Originally Posted by kowbra

I think the best system is to install a proper battery monitoring system and the appropriate shunt to go with it. This will give you all the information you need and then some. You can also pair it to an app on your phone for remote monitoring.

For example, you want to know not just what is going in (which charging source, charging rate, and totals over time) but also the discharging rate and amounts. A big contributor to ruined batteries due to discharging them too much is not being aware of all of the small things that may drain a little at a time. And, if you are boondocking, knowing your power usage will help to optimize when to charge with the generator and when to let the solar system charge. I imagine that could really save some propane usage once you start using it.
Maybe a comparison is having a fuel gauge and using the "instant mpg" gauge on your vehicle... that is a lot more accurate and up to date than a stick in the tank, and can help you drive in a way that saves energy also.

For the Montana Super Solar Flex system, they include the highly rated Victron BM-712.
https://www.victronenergy.com/batter.../bmv-712-smart
and, an option to purchase here...
https://www.amazon.com/Victron-Energ.../dp/B075RTSTKS

We used a competing product in a prior 5th wheel, and I would not be without a battery monitor now. Our new Montana has the Victron as above, and it really does help to monitor and know how to properly charge and protect your batteries.

Hope that helps!
Brad

This above. One of the best purchases Ive made. I didnt go the Victron one and got a cheaper renogy clone just to have some insight on whats going on with my batteries.

https://www.amazon.com/QWORK-Program...ACYGB71JTJWH2T

[Ren]

Pictures of my install. I also purchased a 1/8 inch peice of copper, cut it off
https://www.amazon.com/Copper-Stock-...97&s=hi&sr=1-3

around the 3 inch mark, bent it around 60 degrees or so and drilled two holes in it, one for the batter box terminal, one for the Shunt. Its not the most glamorous install, but its very solid and works. I also have a 10 amp fused 14 guage wire going from the positive battery box terminal to the shunt to provide power for the display. Sounds more complicated that it actually is, fishing the control wire up to the cabinet was the hardest part. I also purchased the 26 foot control wire.

https://www.amazon.com/dp/B0877ZKTJR/ref=emc_b_5_t

The nice thing is, I just dremeled a hold large enough for the control wire for the display in the cabinet and glued the monitor on.

Hope this takes the anxiety out on doing the install for someone.

[dallasrules]

I have the victron 712 and love it. I can bluetooth from my phone and check all the stats on my batteries. Also, I can set a low voltage alarm.

[rohrmann]

Originally Posted by RickyRobert

Have a relatively new Montana 5th wheel with the Solar Flex System. Apparently I have destroyed two very expensive AGM batteries by over-draining them. Would appreciate any help on how I can diagnose the charging system - firstly, when connected to a 50 amp shore power supply (such as I am now in inside winter storage), secondly, if out in the sun when the Solar is working, and thirdly, if I am running the factory installed generator. What "line" to the batteries should I be testing on, and am I looking for voltage or amperage? And I am assuming that the 12V supply switch in the tank valve area must be set to "on". Thanks from a newbie to this facet of RVing.

Be sure that your battery disconnect switch is actually closed. The label is very confusing, does ON mean the switch has the batteries disconnected or does it mean they are connected? The best way to verify the switch is closed is to try pulling the red handle out of the switch. If the handle comes out, the switch is OPEN but if the handle does not come out, the switch is CLOSED, which is where you want it to be for the converter to keep the batteries charged.

[steiny93]

Originally Posted by RickyRobert

Have a relatively new Montana 5th wheel with the Solar Flex System. Apparently I have destroyed two very expensive AGM batteries by over-draining them. Would appreciate any help on how I can diagnose the charging system - firstly, when connected to a 50 amp shore power supply (such as I am now in inside winter storage), secondly, if out in the sun when the Solar is working, and thirdly, if I am running the factory installed generator. What "line" to the batteries should I be testing on, and am I looking for voltage or amperage? And I am assuming that the 12V supply switch in the tank valve area must be set to "on". Thanks from a newbie to this facet of RVing.

To know absolutely for certain go direct to the battery with a multi-meter and measure the voltage at the battery then cycle through the 3 patterns.

In each of your intended charging patterns you should see the voltage at the battery raise to above 12 volts. If you don't see the voltage raise then you know that pattern isn't charging the battery.

Some free advice,
When you are not using the rv disconnect the batteries and don't fight the "keeping it plugged in" battle. Add a disconnect on the negative side and call it good. Disconnected batteries will sit a very long time without discharging while in storage. This will end the problem of showing up at storage and having a dead rv.

[bcrvman]

Originally Posted by RickyRobert

Have a relatively new Montana 5th wheel with the Solar Flex System. Apparently I have destroyed two very expensive AGM batteries by over-draining them. Would appreciate any help on how I can diagnose the charging system - firstly, when connected to a 50 amp shore power supply (such as I am now in inside winter storage), secondly, if out in the sun when the Solar is working, and thirdly, if I am running the factory installed generator. What "line" to the batteries should I be testing on, and am I looking for voltage or amperage? And I am assuming that the 12V supply switch in the tank valve area must be set to "on". Thanks from a newbie to this facet of RVing.

You need what is called a shunt. If you are full time and implementing a full out boondocking setup of 400 to 600 AH of battery then you are probably going to want Victron equipment. If not, then get a Bogart Trimetric. With lead acid you should only drain them down to 50% with lithium 90%.

[Buckfisher]

AGM batteries are a lot more forgiving than standard batteries for draining them too low. Before trashing them, I would put them on a slow charger for a few days and then check the voltage. If you watch the voltage periodically, it should slowly go up to 13 something or 14. When it stops going up, disconnect the charger. After disconnecting the charger, and a few hours pass, it should stabilize around 12.7 or maybe higher. Check again after 24 hours to make sure it isn't loosing voltage. If the voltage holds, the battery is good.

[beeje]

I do not know much about solar, I will admit that. So I cant help out there.
What I did do that really helps out a lot is mounted a cheap LCD meter under the switch control panel.
Every time you walk by it, you can see the current battery voltage.
While being towed, the batteries do not charge very much at all.
When returned to shore power the meter reads around 14.5 volts and settles down to around 13.25 after a while where is stays.

[Buckfisher]

If it isn't charging when towed, you probably have either a blown fuse or a bad connection in that circuit. Check for a blown fuss in your truck's fuse box. Finding a bad connection may take a little longer. I would start at the truck plug receptacle, then rv plug, using a light tester, but it could be anywhere in that circuit.

[beeje]

Originally Posted by Buckfisher

If it isn't charging when towed, you probably have either a blown fuse or a bad connection in that circuit. Check for a blown fuss in your truck's fuse box. Finding a bad connection may take a little longer. I would start at the truck plug receptacle, then rv plug, using a light tester, but it could be anywhere in that circuit.

What I'm trying to say is none of our tow vehicles do a good job at charging the rv batteries while under way. The charge wires are too long and not of heavy enough gauge to do much good. The voltage does go up some when you plug in the umbilical cord, but no where near as much as plugging into shore power.